Image optimization

Every PNG committed to the repo — wordpress.org screenshots and banners, teaser images, OG share cards, avatars, icons — goes through compression before it lands. These files ship to users and are served from wordpress.org's CDN, so bytes matter.

Two-step pipeline, always in this order:

# 1. Lossy quantization to an 8-bit palette (usually 60-70% of the win).
pngquant --quality=80-95 --strip --skip-if-larger --force --ext .png <file>.png

# 2. Lossless recompression on top.
oxipng -o max --strip safe <file>.png

--skip-if-larger means step 1 is a no-op when quantization would not help, so the pair is safe to run on anything. Both steps are idempotent — re-running on an already-optimized file changes nothing.

For a whole directory:

pngquant --quality=80-95 --strip --skip-if-larger --force --ext .png *.png
oxipng -o max --strip safe *.png

Check the result and mention the saving when reporting back:

ls -lh *.png

If a screenshot has fine gradients or text that visibly degrades at 80-95, raise the floor (--quality=90-100) rather than dropping step 1 entirely. Do not commit a PNG straight out of Playwright or an image editor.

Other Formats

• JPEG — jpegoptim --strip-all -m85 <file>.jpg, or /opt/homebrew/opt/mozjpeg/bin/cjpeg -quality 82 -optimize -progressive when encoding from source (mozjpeg is keg-only, so it is not on PATH).
• Resizing / format conversion — vipsthumbnail in.png --size 1200x -o out.png. vips is the fast batch workhorse and uses mozjpeg for JPEG output automatically.
• GIF — gifsicle -O3 --lossy=80 in.gif -o out.gif.
• WebP / AVIF — cwebp -q 80 and avifenc are available, but wordpress.org assets must stay PNG/JPEG.

See CLAUDE.local.md for which of these are installed locally.